I'm right there with ya. I've actually finished all of the exams with the exception of Research in Nursing, but I've still got the Health Assessment, Teaching Across Cultures, Expository Writing, Professional Socialization and Baccalaureate Capstone classes left to take.
My strategy for Community Health was to buy the main recommended text (from an online discount textbook site) and just go through the chapters that seemed to be emphasized in the study guide. Genius, I know.
(Sorry that I don't have any pearls of wisdom there.)
You're right that it is a bit of a guessing game as to the content. It's even trickier not to have the online practice tests available for the BSN exams. One thing I can suggest is to assess your own strengths and weaknesses and budget your time accordingly. As a NICU nurse, I felt I could wing it through much of the maternal/child content, but I spent more time on anything having to do with nursing care of the elderly, for example.
Did you hear about the upcoming changes to the exams? I remember reading that the title (and I guess the content) of Community Health Nursing was going to change some time in the next few months. I assume that you know what you're doing there though.
Good luck to you. There are a few of us on here trudging through the program, so hopefully we can help each other to stick it out.